This study is designed to: (1) produce an animal model of sustained arterial hypertension in centrally debuffered cats by behavioral (classical) conditioning of arterial pressure, (2) to identify any characteristic cardiovascular events or reactivity in cats which will predict the susceptibility of the animals to the development of labile and ultimately sustained arterial hypertension, (3) to examine the role of the arterial baroreceptors in establishing the basal level of arterial pressure, (4) to study the effects of various antihypertensive agents on this model, (5) to examine other possible models of sustained hypertension utilizing central stimulation of the brain and pripheral denervation of the baroceptors.